Military forces of the Democratic People's Republic of Korea in front-line units conducted exercises targeting Republic of Korea loudspeakers used for propaganda broadcasts, Yonhap News Agency reported on Wednesday, citing military officials.

A military official was quoted as saying that DPRK forces have frequently created openings for machine guns in their guard posts near the military demarcation line - the de facto border - inside the Demilitarized Zone.

These openings indicated that DPRK forces are ready to strike targets on the southern side of the DMZ. The ROK believes the targets are its loudspeakers through which its propaganda broadcasts are aired.

On Aug 4, two ROK soldiers were injured in the DMZ after three land mines exploded. Seoul claimed the mines had been planted by DPRK forces underneath a route frequented by ROK border guards.

In retaliation, the ROK military resumed propaganda broadcasts near the border for the first time in about 11 years.

DPRK forces also strengthened artillery exercises in border areas. The ROK military believes that the firing drills were also targeted at the loudspeakers.

Tensions escalated on the Korean Peninsula as the ROK and the United States began their joint annual war game, "Ulchi Freedom Guardian", on Monday. The computer-assisted simulation exercise will run until Aug 28.

The DPRK had strongly protested the drill, calling it a rehearsal for an invasion. The ROK military has said that the exercise is defensive in nature.